Several forms of agricultural crops, such as hay, grass, alfalfa, grain, etc. which have a high moisture content require drying prior to storage in order to prevent fermentation and putrefaction. It is known that by drying such crops prior to storage, substantially improved storage life is obtained. For example, newly cut grass has a moisture content of approximately 80% of its weight. To maintain its quality, the dried young grass must be dehydrated to a point where the moisture content is approximately 12% of its weight whereas for hay the moisture content must be no more than approximately 20% of its weight. The normal method of drying grass or hay is to pass air either heated or unheated through a bed of the crop in order to carry away excess moisture. Such drying has not hitherto been common due to the requirement of having to move the product into and out of the drying apparatus as well as, in many cases, the relatively large expense of the drying apparatus itself. For example, a common type of drying apparatus includes a floor duct system upon which the crop must be placed in order to allow air to be forced through the crop. Following drying, the dried crop must then be removed and placed into storage.
U.S. Pat. No. 4,017,981 issued Apr. 19, 1977 to Ingvaldsen discloses a pyramidal grid covering a blower located on the ground and an air exhaust line leading from the blower to an air inlet. The crop is stacked over the grid and air is drawn in through the inlet, past a heater, out through the grid and through the crop.
U.S. Pat. No. 2,442,344, issued June 1, 1948 to Curtis, U.S. Pat. No. 2,532,530 issued Dec. 5, 1950 to Anderson, U.S. Pat. No. 2,443,865 issued June 22, 1948 to Moffett and U.S. Pat. No. 61,393 issued Jan. 22, 1867 to Burns, all disclose dryers which include a wagon with a grid affixed to the floor thereof into which a crop is placed for drying. Following drying, the dried crop is then removed and placed into storage.
U.S. Pat. No. 3,280,473 issued Oct. 25, 1966 to Sullivan discloses a circular grid raised above a plenum formed between the grid, a circular wall having six wall apertures and the ground for supporting the crop. A conical air and moisture impervious cover extends from the upper periphery of the wall over the crop to an upper air aperture. The aperture is coupled by a flexible duct to an exhaust fan and air is drawn through the wall apertures, into the plenum, up through the grid and crop and out the flexible duct.
U.S. Pat. No. 2,502,205 issued to Collins describes a method of curing bales of hay by forming tunnels in each stack to permit subsequent circulation of air therethrough by a portable air moving apparatus. The tunnels are formed by a deflatable rib-like structure that is placed on the ground prior to stacking the hay and because of the weight of the stack of hay, formation of the tunnel structure in the bottom of the stack is developed. Following completion of the stacking operation, the tunnel forming apparatus is deflated and removed. The portable air moving apparatus is then coupled to an open end of the tunnel and transmits air into the latter which gravitates up through the stack and dries the latter.
Except for Collins, each of the foregoing apparatus requires placement of the crop into a drying apparatus, drying the crop in the apparatus and then subsequently removing and storing the dried crop. Even devices used for tunnelling a stack of hay involve the step of first forming the tunnel and then coupling to the tunnel the portable air moving device. Considering that in particular for hay there are standard forms of bales that are paroduced by commonly used machinery, the requirement of having to form tunnels in the bales is an extra time consuming and therefore expensive step.